(i) Field of the Invention
This invention relates to a method and apparatus for forming coherent clusters.
(ii) Prior Art
Under decreasing temperature conditions, gas condenses into liquid, and then freezes into a solid. For a molecular or atomic beam which is emitted from a nozzle, the temperature drops down rapidly. The atoms or molecules will stick together to form clusters. When the number of atoms or molecules N is greater than 100, they are called ultrafine particles. These particles occupy the boundary between the microscopic and macroscopic world and have been intensively studied. These studies are described in Physics and Chemistry of Small Clusters (NATO ASI Series B: Physics. Vol. 158), Plenum, N.Y. (1987) Edited by P. Jena, B. K. Rao and S. N. Khana; Microclusters, edited by S. Sugano, S. Okinishi Springer-Verlag, Tokyo (1987); Surface Science 156, Part 1 and 2 (1985); Surface Science 106, (1981); J. Phys. (Paris) C-2 (1977); and Chobiryushi-Science and Applications (Kagakusosetsu) (Chemical Review) Vol. 48, Chemical Society of Japan Tokyo (1985).